Cytochrome c is the best understood member of the mitochondrial respiratoy chain, especially with the recent X-ray determination of the crystal structure in both the oxidized and reduced forms, but the mechanism by which it transports electrons from cytochrome c1 to cytochrome oxidase is unknown at the molecular level. The long term goal of the proposed research is to develop and exploit nuclear magnetic resonance (NMR) methods for the study of the interaction of cytochrome c with phospholipid membranes and with cytochrome oxidase, and ultimately to gain a better understanding of the electron transport process. Proton NMR resonances of groups in the interior of cytochrome c will be used to study possible conformation changes in the basic structure of cytochrome c due to association with phospholipid membranes and with cytochrome oxidase. F19 probes will be chemically attached at strategic locations on the exterior of cytochrome c to aid in locating the binding site with cytochrome oxidase and to investigate the nature of this binding site and the electron transport mechanism. NMR methods will be used not only to detect and characterize conformation changes in these proteins, but also to study the dynamics of these changes. It is hoped that these NMR studies will lead to an increased understanding of the detailed mechanism of electron transport and oxidative phosphorylation in the mitochondrial membrane.